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- Girard, R T, et al.
(författare)
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Electronic structure of ZnO(0001) studied by angle-resolved photoelectron spectroscopy
- 1997
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 373:2-3, s. 409-417
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the ZnO(0001) surface was studied by angle-resolved photoelectron spectroscopy. The recorded normal emission spectra give information about the Valence band states as well as the Zn 3d states. The dispersions of the four valence bands observed in the (0001) direction were compared with theory and are in good agreement with recent calculations which consider the Zn 3d electrons as part of the valence band. The Zn 3d states are seen to separate into two groups of four and six bands, which show dispersion with k(perpendicular to). This is in agreement with theoretical results but the location of these states were not accurately predicted. The present photoemission results show that they lie around 10.5 eV below E(F). Two surface states were observed on the (0001) surface. One, at 7.5 eV binding energy, was predicted by theory and is interpreted as arising from the ''back-bondings'' of the Zn 4s-O 2p mixed bulk states. The other one at 4.5 eV below E(F), most likely Zn 4p-0 2p derived, was not predicted by theoretical calculations and this is discussed further in the text. (C) 1997 Elsevier Science B.V.
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| 2. |
- Tjernberg, O, et al.
(författare)
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Influence of magnetic ordering on the NiO valence band
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 54:15, s. 10245-10248
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Tidskriftsartikel (refereegranskat)abstract
- The influence of magnetic ordering on the NiO valence band has been studied by angle resolved photoelectron spectroscopy. Measurements have been performed at temperatures above and below the Neel temperature (T-N), as well as at room. temperature. The results show temperature dependence but no significant changes in the valence band structure are detected in connection to the passing of T-N. The reported data suggest that the magnetic phase transition does not influence the valence band structure significantly.
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| 3. |
- Girard, V, et al.
(författare)
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Pre- and postjunctional inhibitory effects of fenspiride on guinea-pig bronchi
- 1997
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Ingår i: The European respiratory journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 10:5, s. 1015-1020
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Tidskriftsartikel (refereegranskat)abstract
- Fenspiride is a drug with potential benefits in the treatment of obstructive airways disease. It has antibronchoconstriction and anti-inflammatory properties. The aim of this study was to investigate the effect of this drug on the contractions induced in the guinea-pig isolated main bronchus and perfused lung by electrical field stimulation (EFS) or exogenously added agents. Bronchi were stimulated transmurally in the presence of indomethacin 10(-6) M and propranolol 10(-6) M, and isometric tension was measured. In the perfused lung model calcitonin gene-related peptide (CGRP) release was determined in the perfusate fractions as a measure of neuropeptide production. Two successive contractile responses were observed: a rapid cholinergic contraction, followed by a long-lasting contraction due to local release of neuropeptides from C-fibre endings. Fenspiride (10(-6) to 10(-4) M) inhibited the nonadrenergic, noncholinergic (NANC) component of the contraction of the guinea-pig isolated main bronchus induced by EFS. Fenspiride significantly affected contractions induced by exogenously added substance P or [Nle10]-NKA(4-10) only at concentrations higher than 10(-3) M. In the guinea-pig perfused lung, fenspiride inhibited low pH- but not capsaicin-evoked release of CGRP. At higher concentrations (10(-4) M to 3x10(-4) M) fenspiride exhibited a significant inhibitory effect both on the cholinergic component of contractile response induced by EFS in the guinea-pig isolated main bronchus and on exogenously added acetylcholine. In conclusion, the result of this study suggests that fenspiride, in moderate concentrations, reduces the release of neuropeptides, including tachykinins, from sensory nerve endings at a prejunctional level. At higher concentrations, postjunctional actions on bronchial smooth muscle are also present.
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